Since the mid-1960's plaque has been identified as playing at least a major role in causing dental problems both with respect to caries and periodontal disease. However, the actual mechanism by which plaque operates is still subject to conjecture. Plaque, a film of mucus which is produced in the mouth, is a known medium which can harbor bacteria both on the tooth and adjacent gum tissue. It is now generally recognized that removal of plaque is essential for promulgating oral hygiene.
Although substantial research and product engineering has occurred over the last 25 years with a view towards effectively removing plaque, certain difficulties still exist. The following prior art describes the on going efforts of others attempting to solve this long standing problem which has yet evaded solution, and these prior art citations are included to discharge applicant's acknowledged duty to disclose prior art with which he is familiar:
______________________________________ INVENTOR PAT. NO. ISSUE DATE ______________________________________ Cowardin, C. M. 119,745 October 10, 1871 Ripper 1,801,691 April 21, 1931 Stonehill 2,381,142 August 7, 1945 Footer, J. 2,612,177 September 30, 1952 Graham 2,620,104 December 2, 1952 Allen 2,721,014 October 18, 1955 Petitta, M. 2,931,371 April 5, 1960 Chisman 3,160,157 December 8, 1964 Hendy 3,525,460 August 25, 1970 Doiron 3,531,030 September 29, 1970 Haagedoorn 3,650,392 March 21, 1972 Wells, R. L. 3,744,499 July 10, 1973 Thronton 3,837,351 September 14, 1974 Standish et al. 3,838,702 October 1, 1974 Hardwick 3,880,167 April 29, 1975 Thornton 3,896,824 July 29, 1975 Messer, et al. 3,910,282 October 7, 1975 Tarrson, et. al. 3,929,144 December, 1975 Wells, R. L. 3,930,059 December 30, 1975 Ace 3,949,756 April 13, 1976 Pace 3,987,839 October 26, 1976 Herzstein 4,008,836 Februray 22, 1977 Tarrson et al. 4,011,658 March 15, 1977 Guyton, W. C. 4,029,113 June 14, 1977 Oldham, G. R. 4,064,883 December 27, 1977 Negishi, et al 4,070,815 January 31, 1978 Griset, Jr. 4,080,777 March 28, 1978 Naslund 4,133,339 January, 9, 1979 Griset, Jr. 4,155,216 May 22, 1979 Griset, Jr. 4,159,619 July 3, 1979 Perri, S. 4,182,341 January 8, 1980 Griset, Jr. 4,184,316 January 22, 1980 Thomas et al 4,215,478 August 5, 1980 Eaton, II 4,265,258 May 5, 1981 Russell 4,274,565 June 23, 1981 Lubow 4,296,877 October 27, 1981 Weber 4,385,575 May 31, 1983 Paudler 4,441,497 April 10, 1984 Fukuhara 4,512,164 April 23, 1985 Donovan, M. 4,523,600 June 18, 1985 Finkelstein et al 4,583,564 April 22, 1986 Noiles 4,602,636 July 29, 1986 Feuerman 4,667,860 May 26, 1987 Vornholt 4,790,254 December 13, 1988 Noguchi 4,805,292 February 21, 1989 Sos, et. al. 4,817,398 April 4, 1989 Smole, F. T. 4,832,063 May 23, 1989 Dalbo 4,832,240 May 23, 1989 Noguchi 4,901,722 February 20, 1990 Korthoff 5,035,707 July 30, 1991 Caramaschi 5,038,836 August 13, 1991 Siekmann 5,050,625 September 24, 1991 Prou 5,089,012 February 18, 1992 Feuerman 5,129,558 July 14, 1992 Korthoff, et al. 5,133,738 July 28, 1992 ______________________________________
Generally, the techniques for plaque removal are predicated on two principles. The first involves plaque removal through "washing" the plaque from the mouth area by means of liquids. Second, plaque removal has been attempted by mechanical brushing.
With respect to washing, certain mouthwashes are commercially marketed without prescription which purport to be effective in plaque control. These however are not registered with the Food and Drug Administration, and are listed merely as cosmetics. Available research data suggests that these mouthwashes are less than completely effective. A second known liquid, Peridex, is available under prescription and is a known plaque-removing liquid, but is objectionable to the extent that side effects are exhibited in some individuals. These side effects include adverse teeth staining and affection of one's taste perception. Even with an effective liquid, the film-like quality of plaque thwarts highly efficient removal through mere mouthwashing, and is singularly ineffective when trying to remove plaque in the sulcus area of one's mouth, i.e., the narrow trough-like gap between one's tooth and the gum tissue. This is also critical interproximally (in between the teeth) since this is where most periodontal disease and caries occur. When a patient, already afflicted by periodontal disease or for other reasons, uses dental implants, bridges or has had subgingival curettage or surgery performed, interproximal spaces greater than 4 mm exist between teeth and or adjacent the sulcus. This provides greater opportunity for further plaque formation and gum disease.
To a certain extent, plaque formation is not a problem on tooth surfaces that can receive direct mechanical contact with an instrument such as a brush which effectively breaks up the plaque film and therefore allows the plaque and its associated entrained bacteria to be carried away. Many brush manufacturers claim their bristles will go below the gum (in the sulcus) on the buccal and lingual--but not interproximally. Thus, along those areas where direct brush contact is possible, plaque buildup is less of a problem. However, brushes still are quite ineffective in removing plaque both along the area immediately below the gum line, i.e., the sulcus and interproximally. The problem is exacerbated when patients have had periodontal related dental procedures performed.
As knowledge with respect to the role that plaque plays in dental disease has grown, so too has the change in the design of various types of dental floss. While dental floss was once used substantially as a toothpick for the removal of entrained matter caught between teeth, various changes in dental floss appearance, particularly in the last few years reflect the belief that dental floss can be used to remove plaque in areas normally inaccessible by any other means particularly especially when the floss is used daily. Most designs involve contouring the external configuration of nylon or polyethylene to form an abrasive surface which can break up the plaque film under the gum line and between teeth to solve the problem. Earlier attempts have included the use of fibers formed from silk, cotton, nylon or blends thereof.
All of these known prior art flossing structures are less than desirable in that they are either too abrasive which adversely effects the enamel on the tooth, are too sharp which can cause damage to the gum tissue by cutting the gums, or are ineffective in removing the plaque. Moreover, taking this floss under the gum actually causes pain and the patient, therefore, will not take floss under the gum to remove plaque in the normal 3 mm sulci.
Another problem involves the geometry of prior art leaders themselves. Commercially available threaders for use with bridges, implants, etc. must first be threaded with the floss because they do not come pre-threaded. This can be inconvenient and discouraging to a prospective user. Further the geometry of many threaders make their use further frustrating. Among other things, saliva makes the threader too slippery to use.
Another problem is that extremely small threaders may impose a point load on the floss which makes fracture of the floss likely. When this occurs, the floss is entrained in the person's mouth and can be difficult to remove.
Another problem is that small threaders--typically formed by injection molding--are difficult to make without inducing zones of weakness in the threader. Plastic, such as nylon when unstressed or ideally formed, exhibits long molecular chains for greatest tensile strength. "Hairpin" turns (such as adjacent a threaded eyelet) tend to shorten the molecular chain inducing failure of the threader itself upon tensile loading by the floss.
Other threaders exhibit a "knit-line" caused by the flow of the plastic resin around two sides of a core and re-joining downstream from the core. This knit-line is a natural area of weakness and therefore failure.